Why does my tablet lag and back gets warm rather quickly

My Galaxy Tab S 10.5 lags so very badly and gets warm real quick. I deleted all apps that I have installed after I got it tried to see if it still lags and gets warm....the answer is yes...same thing. I then reinstalled my apps.

Had new battery installed approx 4 mos ago, thought maybe that was issue, it did not change problem.

Could it be a hardware issue, like a new motherboard or something?